Rheostat



Feb. 13, 1923. 1,445,324. A. A. KE N T.

RHEOSTAT.

HLED JULY 24. 1922.

L P INVENTOR.

r ATTORNEY.

Patented Feb. 13, 1923.

UNITED STATES PATENT OFFICE.

ARTHUR ATWATER KENT, OF ARDMORE, PENNSYLVANIA.

RHEOSTAT.

Application filed July 24,

To all whom it may concern Be it known that I, ARTHUR A'rwA'rnn KENT, a citizen of the United States, residing at Ardmore, county of Montgomery, and

State of Pennsylvania, have invented certain new and useful Improvements in Rheostats, of which the following is a specification.

My invention relates to rheostats, of general application, and particularly those suited for varying the strength of current flowing through, and therefore varying the incandescence of, the cathodes, as filaments, of thermionic devices, such as audions and the like, employed in the radio art and in other relations.

My invention resides in features of structure, arrangement and combination of the character hereinafter described and claimed.

For an illustration of some of the various forms my invention may take, reference is to be had to the accompanying drawing, in which:

Fig. 1 is a vertical sectional view, parts in elevation, of a rheostat embodying my invention.

Fig. 2 is a front elevational view of the same.

Fig. 3 is a rear elevational view of the same, partly in section.

Fig. 4 is a vertical sectional view, partly in elevation, of a modified form of rheostat.

Figs. 5 and 6 are front and side elevational views of the same.

Referring to Figs. 1, 2 and 3, P is a panel or support of any suitable material, either conducting or insulating, upon which the rheostat structure is mounted. A sheet metal base member B has at its opposite ends the integral upstanding ears or lugs L, L,

and also, preferably, the integral extension E, of any suitable form, as semi-circular, as indicated.

Wound about a strip S, of insulating ma terial, as indurated fibre or the like, is the resistance wire or conductor R, covering a bowed or semi-circular portion of the strip S between its ends, by which it is supported upon and secured to the lugs L.

Extending through registering holes in one lug L and one end of the strip S is a screw 8, upon which is threaded a nut member n, thereby holding and clamping the strip S to the lug L. The nut n and the e0- 56 acting nut 0 form a binding post or one 1922. Serial No. 576,951.

terminal of the rheostat, the binding post structure serving to clamp and connect the circuit conductor 7;, which accordingly, by the structure described, is in electrical communication with the base B, the end 1' of the conductor R being free or unconnected.

Through registering holes in the other lug L and the other end of the strip S extends a screw 8 upon which is threaded the nut member 02 between which and the end of the strip S is clamped the other end r of the resistance .wire R, whereby oneend of the resistance conductor R is in elec trical communication with the binding post formed by the nut 72 and the co-acting nut member 0 which serves to connect and clamp the other circuit conductor p which is accordingly in electrical communication with one end of the resistance B. By bushing Z) and washer w, both of insulating material, the screw 8 is insulated from the lug L and base B.

Extending through registering holes in the panel or support P and the base B, or its extension E, is the externally threaded metal bushin A having the flange abutting against the member P and having on its other end the metal nut a by which the flange f is drawn snugly against the panel P and by which the base B and the parts attached thereto are secured to the panel P. Additional means, as screws or bolts 0, are also preferabl provided for holding the base B and t e parts carried thereby to the support or panel P.

Rotating and bearing within the sleeve or bushing A is the metal shaft d, upon which is secured by the screw 6 the metal bushing 9 having the end h of reduced diameter extending through a hole in the metallic contact lever i, which is fixedly secured to the bushing g by spinning over or riveting the end of the aforesaid portion 71-. The contact lever 2' has a struck-up contact portion j, which engages the resistance wire R.

The contact lever is more or less resilient, and its tension, as determined by the position of the bushing 9 upon the shaft (Z, determines the amount of pressure exerted by the contact upon the resistance R, the 105 bushing being adjustable to different positions upon the shaft (Z.

H is a knob or handle, preferably of molded insulating material, as condensite, bakelitel or the like, having molded therein 110 an interiorly threaded insert into which is threaded one end of the shaft d, in the manner hereinafter described in connection with Fig. 4.

Between the flange 7' and the knob H is disposed the pointer or indicator I, which rotates with the knob H and the shaft (l to indicate to the operator the relative position of the contact j upon the resistance R. For this purpose, there may be provided upon the panel or support P a scale is, Fig. 2.

The indicator I may be cemented, so'ldered or otherwise secured to the shoulder on the shaft cl, or the indicator I may be held by the pressure exerted thereon by the knob H and the shoulder on the shaft (Z.

By turning the lamb H, the contact 7' moves to different positions upon the resistance B, and accordingly different amounts of resistance R are in circuit between the binding posts 0 and 0 By preference, the lugs L are of such height or project to such extent beyond the upper edge of the strip S that they serve as stops for limiting the range of movement of the contact lever 2'.

While a rheostat of the character illustrated in Figs. 1, 2 and 3 is more particularly suitable for mounting upon the rear of a panel and operable from the front thereof, the structure may also be of a character in which the rheostat structure and its operating handle are upon the same side of the support or panel. Such a modification is illustrated in Figs. 4, 5 and 6, in which the resistance conductor is mounted upon a base member B, as hereinbefore described. In this case, the screws or bolts 0, or equivalent, are employed for securing the base member to the panel or support P. Upon the base member B or its extension E is secured a metallic sleeve or bushing A having a portion of reduced diameter m which is expanded in the hole in the base B or spun over or riveted thereto, as indicated in Fig. 4. Rotating and having a bearing in the bushing A is the metallic shaft 03, having a threaded end (I of smaller diameter threaded into the interiorly threaded -metallic insert 27 embedded or molded in the handle or knob H. The con tact arm or lever z is clamped against the shoulder of the shaft cl formed at its junc tion with its end 9 of smaller diameter, the knob or handle H being the clamping memher which, when threaded on to the end 1 secures the contact member z' against the shoulder of the shaft d to cause the same to electrically connect and rotate therewith. It will be understood, however, that the contact lever 2' may be soldered or otherwise secured to the shaft (Z. The shaft (I has at its other end a head a, which thrusts against the adjacent end of the sleeve or bushing A, and so serves to put tension upon the contact lever i to cause sufficient pressure between the contact j and the resistance R.

For the resistance element, as conductor B, there may be employed any suitable material. By preference, the resistance element is in the form of a metallic wire, as shown, and is preferably of a character having small or substantially zero temperature coefficient.

What I claim is:

1. Rheostat structure comprising a metallic base member, upstanding lugs integral therewith, a strip of insulating material having its ends secured, respectively, to said lugs, a resistance element on said strip, a rotatable contact lever engaging said resistance element, said lugs forming stops for said contact lever, and a bearing on said base member for said contact lever.

2. Rheostat structure comprising a metallic base member, upstanding lugs integral therewith, a strip of insulating'material having its ends secured to said lugs, a resistance element on said strip, binding posts securing the ends of said strip to said lugs and electrically connected, respectively, to said resistance element and to said base member, and a movable contact lever engaging said resistance element and carried bv and electrically connecting with said base member.

3. Rheostat structure comprising a sheet metal base member, upstanding Jugs stamped therefrom, a strip of insulating material secured at its ends to said lugs, a resistance element on said strip, a bushing on said base member, a shaft rotatable in said bushing, and a contact lever carried by said shaft andengaging said resistance element.

4. Rheostat structure comprising a metallic base member, upstanding lugs thereon, a strip of insulating material secured at its ends to said lugs, a resistance element on said strip, a rotatable shaft, a bushing secured thereto, a contact lever engaging said resistance unit and having an aperture through which said bushing extends, said bushing. extending on opposite sides ofsaid contact lever beyond the limits of said aperture for holding said lever.

Rheostat structure comprising a metallic base member, upstanding lugs thereon, a strip of insulatingmaterial secured at its ends to said lugs, a resistance conductor on said strip, a bushing extending through said base member and having on one end a flange and threaded on its other end, a clamping nut engaging said threaded end, a shaft rotatable in said bushing, a contact lever secured to said shaft and engagin g said resistance element, and an operating handle on said haft adjacent said flange.

6. Rheostat structure comprising a metallic base member, upstanding lugs thereon, a strip of insulating material secured at its ends to said lugs, a resistance conductor on said strip, a bushing extending through said base member and having on one end a flange and threaded on its other end, means cooperating with said threaded end to hold the bushing in place, a shaft rotatable in said bushing, a contact lever secured to said shaft and engaging said resistance element,

an operating handle on said shaft adjacent said flange, and means for adjusting the point of attachment of said contact lever longitudinally of said shaft.

7. Rheostat structure comprising a metallic base member, upstanding lugs thereon, a strip of insulating material secured at its ends to said lugs, a resistance element on said strip, a bearing sleeve having a portion of reduced diameter extending through an aperture in said base member and extending through said base member beyond the limits of said base member, means at the opposite ends of the sleeve for retaining it in said aperture, a shaft having a bearing in said sleeve, and a contact lever attached to said shaft and engaging said resistance element.

8. Rheostat structure comprising a metallic base member, upstanding lugs thereon, a strip of insulating material secured at its ends to said lugs, a resistance element on said strip, a bearing sleeve having a portion of reduced diameter extending through an aperture in said base member and extending over said base member beyond the limits of said aperture, means co-operating with said extended portion of the sleeve to secure it to the base member, a shaft having a bearing in said sleeve, a contact lever attached to said shaft at a portion thereof remote from the point of attachment of said sleeve to said base member, and an operating handle secured to said shaft.

9. Rheostat structure comprising a sheet metal base member, upstanding lugs stamped therefrom, a strip of insulating material having its ends adjacent said lugs, a resistance element on said strip, and binding posts securing said ends of said strip to said lugs and connected, respectively, to said resistance element and one of said lugs.

10. Rheostat structure comprising a sheet metal base having two diametrically opposite ears struck up therefrom, an insulat ing member of semi-circular form having its ends respectively secured to the cars, a resistance element Wound upon the insulating member, a terminal for one end of the resistance element secured to, but insulated from, one of said ears, the other end of the resistance element being supported by and electrically connected to the other one of said ears, and a contact finger pivotally supported by said base and having a portion thereof slidable along the resistance element.

In testimony whereof I! have hereunto affixed my signature this 18th day of July, 1922.

ARTHUR ATWATER KENT. 

